Third generation mobile telecommunications systems aim at providing end-users, apart from terminal and personal mobility, with enhanced services. Compared to second generation systems, enhancements that will cover features all the way between the end-user and the core network elements are required, i.e. from mobile terminals to radio access and fixed networks. The UMTS is such a third generation system, wherein, for example, Asynchronous Transfer Mode (ATM) technologies may be selected so as to represent a business environment and support fixed ATM terminals.
Delivering wide band multimedia services will require additional performance compared with today's wireless standards. In this respect, research has been conducted focusing on WCDMA which fully supports both packet- and circuit-switched communications such as Internet browsing and land line telephone services, respectively.
WCDMA is based on a modern, layered network-protocol structure similar to the protocol structure used in, for instance, GSM networks. This will-facilitate the development of new wireless wide band multimedia applications. With increasing demand for next-generation mobile telephone services, there will be a new set of requirements on a wireless systems, such as:                support for high speed data communication;        support for both packet- and circuit-switched services, such as internet traffic and video conferencing;        higher network capacity, better usage of the frequency spectrum, each user will require more capacity compared to today's voice services;        support for several connections.        
Users will, for instance, be able to browse the Internet in parallel to voice calls and/or video conferencing.
Recently, the European Telecommunications Standards Institute (ETSI) decided on WCDMA as the radio technology for the paired bands of the UMTS. The same applies to the standardization bodies of Japan and the USA. Consequently, WCDMA is the common radio technology standard for third-generation wide-area mobile communications in Europe, North America and Asia.
The WCDMA concept is based on a totally new channel structure for all layers (L1 to L3) build on technologies such as packet-data channels and service multiplexing. The new concept also includes pilot symbols and a time-slotted structure.
In practice, certain key parameters in WCDMA and GSM have been harmonized in order to achieve an optimum solution for dual-mode GSM/UMTS terminals as well as GSM/UMTS hand-over. This will facilitate today's users easy access to third-generation services through dual-mode terminals, as will be the case with UMTS/GSM terminals.
In WCDMA systems, user plane data entities (in the following referred to as transport blocks TB) need to be transported between a radio network controller (RNC) and a base station (BS) of a mobile network like the GSM network. A frame layer control protocol exists that handles the transmission between the above two-network elements (BS and RNC), which is referred to as Radio Block Transport Protocol (RBTP) in the following.
The RBTP is adapted to attach to a transport block TB all information which the layers 2/3 in the RNC and the layer 1 in the BS need to exchange. This information is necessary for synchronization (e.g. a frame number to synchronize the transmission), outer loop PC (e.g. a frame reliability information and a power control command), macro diversity combining (e.g. a system frame number and the L1 cyclic redundancy check), indication of L1 processing to be done (e.g. a transport format indicator TFI), and identification of a channel to which the present TB belongs.
According to a known solution, a fixed structure of the RBTP frame for one kind of channel is used, e.g. there is one structure for a dedicated channel with a fixed number of bit reserved for every field.
However, the parameters necessary to be attached to the TB are different for different kind of transport channels that the WCDMA system supports (e.g. common channels, dedicated channel with and without soft handover possibility, high and low bit rate, fixed or variable bit rate, best effort packet data channels), because the nature of the channels and the characteristic of the data transmitted over them are different.
Therefore, the above known solution leads to the drawback that the transmission link is not efficiently used, since the RBTP frame may contain information which is not necessary or which can be specified with a minor number of bits, due to the specific characteristic of the channel.